WASHINGTON (AP) — Black people are arrested for possessing marijuana at a higher rate than white people, even though marijuana use by both races is about the same, the American Civil Liberties Union reports in a new study.

The analysis of federal crime data, released Tuesday, found marijuana arrest rates for blacks were 3.73 times greater than those for whites nationally in 2010. In some counties, the arrest rate was 10 to 30 times greater for blacks.

An overall increase in marijuana possession arrests from 2001 to 2010 is largely attributable to drastic increases in arrests of black people, the ACLU said.

The report comes at a time when Colorado and Washington have become the first states to legalize adult possession of small amounts of nonmedical marijuana. A number of states and Washington, D.C. allow medical marijuana. Federal law still prohibits its use. Some states and some cities have eased punishments for possession of smaller amounts.

Ezekiel Edwards, lead author of the study, attributed the disparate arrest rates to racial profiling by police seeking to pad their arrest numbers with “low-level” arrests in “certain communities that they have kind of labeled as problematic.”Marijuana is displayed during the grand opening of the Seattle location of the Northwest Cannabis Market, for sales of medical marijuana products, Feb. 13, 2013.(Photo: Elaine Thompson, AP)

Blacks were arrested at a rate of 537 per 100,000 people in 2001. In 2010, their arrest rate rose to 716 per 100,000. The 2001 number for white people was 191 per 100,000 and rose to 192 per 100,000 in 2010, the ACLU said.

Despite the disparate rates, far more whites were arrested in 2010 for marijuana possession, 460,808, compared to blacks, 286,117.

Police simply operate from the standpoint that “the use of marijuana is a crime,” said Jim Pasco, executive director of the National Fraternal Order of Police, who had not yet seen the ACLU report.

Arthur Burnett Sr., a retired judge of the Superior Court of the District of Columbia, said his 40 years on the bench showed him that police concentrate their numbers in black communities. It’s easier to catch people with marijuana in communities where there are “open-air” drug markets, rather than looking in homes, basements or country clubs, said Burnett, the CEO of the National African American Drug Policy Coalition.

Burnett said his coalition supports forming a commission that would determine whether to treat marijuana like tobacco, in which people are warned about consequences of its use. It would also examine the harshness of penalties for using pot.

“We don’t need to treat it like heroin and cocaine,” Burnett said.

The ACLU supports legalization of marijuana and regulation through taxation and licensing. It also supports eliminating criminal and civil penalties for marijuana possession. If those two options are not possible, the group supports punishment for marijuana possession with only civil penalties.

The unequal arrests rates are not confined to a single U.S. region or to urban areas with larger black populations, the ACLU said. That discrepancy is found throughout the country, regardless of the size of the black population of the location and at all income levels, the data shows.

African Americans living in counties with the highest median household incomes, $85,000 to $115,000, are two to eight times more likely to be arrested for marijuana possession than whites. In counties with median household incomes of $22,000 to $30,000, the arrest rate for blacks is 1.5 times to five the rate as for whites, the report said.

When it comes to marijuana use, about 14 percent of blacks and 12 percent of whites reported in 2010 that they had used the drug during the previous year, according to data that the ACLU obtained from the federal National Drug Health Survey. Among people ages 18-25, use was greater among whites.

The findings are hardly surprising to the African American community.

Ben Jealous, president and CEO of the National Association for the Advancement of Colored People, said arrest disparities have led to mass incarceration and criminalization of African Americans.

“Any arrest, even for marijuana, is a blot on someone’s record and an impediment to future jobs and opportunities,” Jealous said. “For these reasons, a number of NAACP state conferences (chapters) have supported the decriminalization of marijuana.”